Working Memory Model
WMM: | The working memory model replaces the concept of a unitary STM put forward by Atkinson and Shiffrin. It suggests that STM is a multi-component flexible system concerned with active processing and short-term storage of information |
Baddeley and Hitch WMM: | According to them STM is a working memory with a complex and flexible system comprised of three main components.
Aided by two subsidiary slave systems:
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The central executive:
Has control of:
Evaluation:
Eslinger & Damasio’s: | A supervisory component that has overall control.
Monitoring and correcting errors starting the rehearsal process, switching attention between tasks, inhibiting irrelevant information and retrieving information from LTM.
It has limited capacity but can process information from any sensory modality.
Supported by two slave systems.
It could be argued that the role of the CE is a little vague. What exactly is ‘directing attention’ and ‘allocating resources?
It is possible that the CE, like the other aspects of the model, is also not unitary.
Their patient EVR performed well on reasoning tasks but not on problem solving tasks. Given that both tasks would involve the CE this suggests that the CE has sub-components involved with each task respectively. |
Slave systems:
The phonological loop:
The visuo-spatial sketchpad:
| Can be used as storage systems thereby freeing up some of the central executive's capacity to deal with more demanding information processing tasks.
The slave systems have separate responsibilities and work independently of one another.
It is a limited capacity, temporary storage system for holding verbal information in a speech-based form.
It is a limited capacity temporary memory system for holding visual and spatial information.
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The three components – simple explanations:
Central executive:
The phonological loop:
The visuo-spatial sketchpad |
This can be described as attention in has limited capacity and controls two slaves that also have limited capacity.
Holds speech-based information.
STM for visual and spatial information. |
Baddeley and Loie: | Refined this model.
The phonological loop consists of a passive storage system called the phonological store which is linked to an active rehearsal system called articulatory loop – whereby words can be maintained by sub vocal reputation.
Also, visuo-spatial sketchpad consists of a passive visual store called the visual cache (store) which is linked to an active inner scribe that acts as a rehearsal mechanism. |
Baddeley – Episodic buffer: | The episodic buffer was added by Baddeley in 2000. He proposed that tasks such as remembering prose require quite complex information processing. We must know what words mean, how words relate to other words in sentences, how sentences are structured and combined into meaningful chucks called paragraphs. This kind of semantic analysis requires information from LTM therefore there must be an additional subsystem (episodic buffer) that integrated information in working memory with information in LTM.
Hitch & Baddeley’s findings support the existence of the qualitatively different sub-components of working memory as proposed by the model. |
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Baddeley and Hitch:
KF study:
What did they do to test it?
How does this prove MSM right or wrong?
Results & conclusion: | Baddeley and Hitch decided to approach STM research in a novel way and asked, ‘what is it for’. Atkinson and Shiffrin's model of memory considered STM a unitary store. They contested this and suggested some research to undermine this.
The KF study supports the working memory model. KF suffered brain damage from a motorcycle accident that damaged his short-term memory. KF’s impairment was mainly for verbal information – his memory for visual information was largely unaffected.
To test this idea Baddeley and hitch devised the dual task technique. They asked P’s to perform a reasoning task (a sentence checking task) while simultaneously reciting aloud a list of six digits.
If digit span really is a measure of maximum STM capacity P’s would show impaired performance on the reasoning task because STM would be fully occupied with retaining the six digits.
However, they found that P’s made very few errors. Baddeley and Hitch concluded that the STM must have more than one component and must do more than just storage. |
Baddeley and Hitch theory: | They saw STM as a sort of workspace where a variety of operations could be carried out on both old and new memories. They concluded that two tasks can be carried out simultaneously in STM provided they are dealt with by different components of the memory system. They formulated their idea into the WMM. |
Patients with brain damage:
Shallice & Warrington:
Patients with brain damage contd. | There is evidence from cognitive-neurological studies on patients with brain damage which supports the working memory model.
Found that patient KF had difficulties recalling auditory info from STM but not visual info.
This suggests that his damage mainly affected the phonological loop as he appeared to be able to use the visuo-spatial sketch pad. This also supports the proposed idea of multiple components to STM as proposed by the WMM.
However, there are several limitations associated with studies of patients with brain damage most studies of brain damage are case studies; whist case studies provide a lot of detail the subjects may have unique characteristics which mean that they are not representative of anyone else except themselves. It is also not possible to make before and after comparisons of their memory deficits. The trauma of the brain injury may have resulted in numerous changes in behavior. These limitations undermine the extent to which we can rely on studies of patients with brain damage to evaluate the WMM. |
Bunge et al - FMRI scans: | Found that when P’s were doing a dual-task FMRI scans showed significantly more activation. This shows that the increased attentional demands of the two simultaneous tasks increased brain activity. This provides support for the proposed role of the central executive as the aspect which directs attention and allocates resources. |